KR102423374B1 - Apparatus and method for transmitting a reservation signal in wireless communication system - Google Patents

Abstract

The present disclosure relates to a 5G (5th generation) or pre-5G communication system for supporting a higher data rate after a 4th generation (4G) communication system such as Long Term Evolution (LTE). According to various embodiments of the present disclosure, a method of operating a terminal for uplink transmission in an unlicensed band of a wireless communication system includes a process of receiving downlink data from a base station, and after receiving the downlink data, uplink transmission The process of performing a listen before talk (LBT) for, and the process of transmitting a first reservation signal based on the LBT end time and subframe boundary (subframe boundary), and based on the subframe boundary, the base station and transmitting uplink data to

Description

Apparatus and method for transmitting a reservation signal in a wireless communication system

BACKGROUND This disclosure relates generally to a wireless communication system, and more particularly, to an apparatus and method for transmitting a reservation signal in a wireless communication system.

Efforts are being made to develop an improved 5th generation (5G) communication system or a pre-5G communication system in order to meet the increasing demand for wireless data traffic after commercialization of the 4G (4th generation) communication system. For this reason, the 5G communication system or the pre-5G communication system is called a 4G network after (Beyond 4G Network) communication system or an LTE (Long Term Evolution) system after (Post LTE) system.

In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to alleviate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, in the 5G communication system, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used. ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud radio access network, cloud RAN), an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and reception interference cancellation (interference cancellation) Technology development is underway.

In addition, in the 5G system, Hybrid Frequency Shift Keying and Quadrature Amplitude Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), which are advanced coding modulation (Advanced Coding Modulation, ACM) methods, and Filter Bank Multi Carrier (FBMC), an advanced access technology, ), Non Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA) are being developed.

LTE-LAA (licensed-assisted access) is a technology for operating an LTE system based on carrier aggregation (CA) of licensed and unlicensed band frequencies for stable access and transmission speed improvement of terminals. . Unlike the LTE cellular system that uses only the allocated licensed band, the channel to be used for coexistence with different communication systems (eg, wireless fidelity, WiFi and Bluetooth) using the unlicensed band. A procedure is required to confirm whether this is assigned to another terminal. The terminal may check whether a channel is allocated to another node by performing a listen before talk (LBT) procedure during a clear channel assessment (CCA) slot period. If another node occupies the channel, serious performance degradation may occur because transmission can take place after a long time elapses until the channel is occupied according to the next LBT.

Based on the above discussion, the present disclosure provides an apparatus and method for transmitting a reservation signal in a wireless communication system.

In addition, the present disclosure provides an apparatus and method for occupying an inter-transmission channel in a wireless communication system.

The present disclosure also provides an apparatus and method for occupying a channel in a transmission in a wireless communication system.

In addition, the present disclosure provides an apparatus and method for transmitting a message including information necessary for a listen before talk (LBT) procedure in a wireless communication system.

According to various embodiments of the present disclosure, a method of operating a terminal for uplink transmission in an unlicensed band of a wireless communication system includes a process of receiving downlink data from a base station, and after receiving downlink data, LBT ( listen before talk) and the process of transmitting a first reservation signal (reservation signal) based on the LBT end time and subframe boundary (subframe boundary), and based on the subframe boundary, uplink data may include the step of transmitting to the base station.

According to various embodiments of the present disclosure, a method of operating a base station for downlink transmission in an unlicensed band of a wireless communication system is based on a process of transmitting downlink data to a terminal, the transmission completion time, a predetermined time, and a subframe boundary. to transmit the first reservation signal, and receiving uplink data from the terminal based on the subframe boundary. The predetermined time may be a time for the terminal to perform LBT in order to transmit the uplink data.

According to various embodiments of the present disclosure, a terminal device for uplink transmission in an unlicensed band of a wireless communication system may include a transceiver, a memory, and a processor. The processor, from the base station, receives downlink data, and after receiving the downlink data, performs LBT (listen before talk) for uplink transmission, the LBT end time and subframe boundary (subframe boundary) based on , transmit a first reservation signal, and based on the subframe boundary, may be configured to transmit uplink data to the base station.

According to various embodiments of the present disclosure, a base station apparatus for downlink transmission in an unlicensed band of a wireless communication system may include a transceiver, a memory, and a processor. The processor transmits downlink data to the terminal, transmits a first reservation signal based on the transmission completion time, a predetermined time, and a subframe boundary, and receives uplink data from the terminal based on the subframe boundary may be configured to receive. The predetermined time may be an LBT execution time of the terminal for transmitting the uplink data.

According to various embodiments of the present disclosure, a method of operating a base station in an unlicensed band of a wireless communication system includes a process of determining a type of a reservation signal, a process of determining a reservation signal timing according to the determined type, and the determined type and The method may include transmitting a message including information on the reservation signal timing to the terminal. The type of the reservation signal may be determined according to whether the base station and the terminal transmit the reservation signal.

The apparatus and method according to various embodiments of the present disclosure may protect downlink transmission exceeding the maximum channel occupation period by transmitting a reservation signal in transmission.

The apparatus and method according to various embodiments of the present disclosure may prevent a channel occupation failure of a terminal by transmitting a reservation signal between transmissions.

Effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be.

1 illustrates an environment of a wireless communication system according to various embodiments of the present disclosure;
2 illustrates a functional configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure.
3 illustrates a functional configuration of a base station in a wireless communication system according to various embodiments of the present disclosure.
4 illustrates an operation flow of a terminal for occupying a channel in a wireless communication system according to various embodiments of the present disclosure.
5A and 5B illustrate an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure.
6A and 6B illustrate an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure.
7 illustrates an operation flow of a base station for channel occupation in a wireless communication system according to various embodiments of the present disclosure.
8A and 8B illustrate an example of a subframe for transmission of a reservation signal between transmissions of a base station in a wireless communication system according to various embodiments of the present disclosure.
9A and 9B illustrate an example of a subframe for transmission of a reservation signal between transmissions of a base station in a wireless communication system according to various embodiments of the present disclosure.
10A and 10B illustrate an example of a subframe for transmission of a reservation signal between transmissions of a base station and a terminal in a wireless communication system according to various embodiments of the present disclosure.
11A and 11B illustrate an example of a subframe for transmission of a reservation signal between transmissions of a base station and a terminal in a wireless communication system according to various embodiments of the present disclosure.
12 illustrates an operation flow of a base station for channel occupation in a wireless communication system according to various embodiments of the present disclosure.
13A and 13B illustrate an example of a subframe for transmission of a reservation signal within transmission in a wireless communication system according to various embodiments of the present disclosure.
14A and 14B illustrate an example of a subframe for transmission of a reservation signal within transmission in a wireless communication system according to various embodiments of the present disclosure.
15 illustrates an example of a subframe for transmission of a reservation signal within transmission in a wireless communication system according to various embodiments of the present disclosure.

Terms used in the present disclosure are used only to describe specific embodiments, and may not be intended to limit the scope of other embodiments. The singular expression may include the plural expression unless the context clearly dictates otherwise. Terms used herein, including technical or scientific terms, may have the same meanings as commonly understood by one of ordinary skill in the art described in the present disclosure. Among the terms used in the present disclosure, terms defined in a general dictionary may be interpreted with the same or similar meaning as the meaning in the context of the related art, and unless explicitly defined in the present disclosure, ideal or excessively formal meanings is not interpreted as In some cases, even terms defined in the present disclosure cannot be construed to exclude embodiments of the present disclosure.

In various embodiments of the present disclosure described below, a hardware access method will be described as an example. However, since various embodiments of the present disclosure include technology using both hardware and software, various embodiments of the present disclosure do not exclude a software-based approach.

In this document, expressions such as “A or B” or “at least one of A and/or B” may include all possible combinations of items listed together. Expressions such as "first," "second," "first," or "second," can modify the corresponding elements, regardless of order or importance, and to distinguish one element from another element. It is used only and does not limit the corresponding components. When an (eg, first) component is referred to as being “connected (functionally or communicatively)” or “connected” to another (eg, second) component, that component is It may be directly connected to the component or may be connected through another component (eg, a third component).

In this document, "configured (or configured to)" means "suitable for," "having the ability to," "modified to, ," "made to," "capable of," or "designed to," may be used interchangeably. In some contexts, the expression “a device configured to” may mean that the device is “capable of” with other devices or components. For example, the phrase “a processor configured (or configured to perform) A, B, and C” refers to a dedicated processor (eg, an embedded processor) for performing the operations, or by executing one or more software programs stored in a memory device. , may mean a general-purpose processor (eg, a central processing unit (CPU) or an application processor) capable of performing corresponding operations.

With an increase in usage of radio terminals and the like, there is a growing demand for an increase in radio resources. In order to efficiently use limited resources, the case where two communication systems having different access methods share resources is increasing. When two communication systems coexist while sharing the same band, fairness must be ensured between the two communication systems. As a coexistence technology to ensure fairness between two communication systems so that a channel is not used exclusively by one system, a licensed assisted access (LAA) procedure, including listen before talk (LBT) It is described. On the other hand, a reservation signal (reservation signal) may be used to compensate for the channel band occupancy due to LBT.

Hereinafter, the present disclosure relates to an apparatus and method for transmission of a reservation signal in a wireless communication system. Specifically, the present disclosure describes operations for protecting downlink transmission exceeding the maximum channel occupancy period in an unlicensed band, and preventing the UE from failing to occupy a channel for uplink transmission.

Hereinafter, definitions of terms used in the present disclosure are as follows. The 'reservation signal in transmission' refers to a signal transmitted by the base station between downlink transmissions in order to protect downlink channel occupation and downlink transmission in continuous downlink transmission. The 'inter-transmission reservation signal' is a signal transmitted by a base station or a terminal between downlink transmission and uplink transmission in order to occupy a channel for uplink transmission and protect uplink transmission in uplink transmission following downlink transmission. refers to

In addition, the present disclosure is provided in some communication standards (eg, a long term evolution (LTE) system defined by 3rd Generation Partnership Project (3GPP), an LTE-advanced (LTE-A) system, and an Institute of Electrical and Electrical Engineers (IEEE). Although various embodiments are described using terms used in the defining 802.11 system), this is only an example for description. Various embodiments of the present disclosure may be easily modified and applied in other communication systems.

1 illustrates a wireless communication environment 100 according to various embodiments of the present disclosure.

Referring to FIG. 1 , FIG. 1 illustrates a base station 110 , a first terminal 120 , a second terminal 130 , and a third terminal 140 as part of nodes using a wireless channel in a wireless communication environment 100 . Each of the base station 110, the first terminal 120, the second terminal 130, or the third terminal 140 may be a node supporting an unlicensed band.

The base station 110 is a network infrastructure that provides wireless access to nodes located within coverage. Here, in addition to the base station, the base station is an 'access point (AP)', 'eNodeB, eNB', '5G node (5th generation node)', '5G node ratio (5G NodeB, NB)' )', 'wireless point', 'transmission/reception point (TRP)', 'digital unit (DU)', 'radio unit (RU), remote radio equipment ( remote radio head, RRH) or other terms having an equivalent technical meaning.

The base station 110 has a coverage 111 that is defined as a certain geographic area based on a distance that can transmit a signal. The base station 110 may communicate with a plurality of nodes within the coverage area 111 . For example, the base station 110 may communicate with the first terminal 120 or the second terminal 130 located within the coverage 111 . According to various embodiments, the base station may transmit a dummy signal or a wireless fidelity (WI-Fi) preamble signal to occupy a channel of an unlicensed band. However, the present disclosure is not limited thereto, and other various types of signals for channel occupation may be transmitted. Here, the Wi-Fi preamble may be referred to as a 'wireless LAN preamble'.

The first terminal 120, the second terminal 130, or the third terminal 140 is a device used by a user and performs communication with the base station 110 through a wireless channel. In some cases, at least one of the first terminals 120 may be operated without the user's involvement. For example, the first terminal 120, the second terminal 130, or the third terminal 140 is a device that performs machine type communication (MTC) and may not be carried by the user. Here, the first terminal 120, the second terminal 130, or the third terminal 140 is a 'user equipment (UE)', a 'mobile station', and a 'subscriber station' in addition to the terminal. , 'remote terminal', 'wireless terminal', 'electronic device', or 'user device', 'node' or equivalent technical meaning Branches may be referred to by different terms. A terminal according to various embodiments of the present disclosure is, for example, a smartphone, a tablet PC, a mobile phone, a video phone, an e-book reader, a desktop PC, a laptop PC, a netbook computer, a workstation, a server, a PDA, a PMP (portable PMP) multimedia player), an MP3 player, a medical device, a camera, and at least one of a wearable device.

The coverage 121 may mean a geographic area in which the first terminal 120 may perform communication. The first terminal 120 may communicate with network objects existing within the coverage 121 . Here, the network objects may include a terminal or a base station different from the first terminal 120 . For example, the first terminal 120 may communicate with the base station 110 and the third terminal 140 located within the coverage 121 . However, the first terminal 120 may not be able to communicate with the second terminal 130 existing outside the coverage 121 .

The coverage 131 may mean a geographic area in which the second terminal 130 can perform communication. The second terminal 130 may communicate with network objects existing within the coverage 131 . For example, the second terminal 130 may communicate with the base station 110 existing within the coverage 131 . However, the second terminal 130 may not be able to communicate with the first terminal 120 or the third terminal 140 existing outside the coverage 131 .

The wireless communication environment 100 may be a wireless environment in which a licensed band and an unlicensed band coexist. The base station 110 and the first terminal 120 (the second terminal 130 and the third terminal 140) may be devices supporting LAA. The base station 110 and the first terminal 120 may occupy the channel after performing the LBT procedure in order to operate in the unlicensed band. Hereinafter, the channel, which is an object of determining whether to occupy, refers to a channel of an unlicensed band. The base station 110 may check that the channel of the unlicensed band is not occupied through the LBT procedure. For example, the base station 110 may perform LBT in transmission. The base station 110 may determine a maximum (maximum) channel occupation time (COT) for occupying the unlicensed band. Here, the maximum channel occupancy time means the maximum value of the time defined to perform uplink data transmission and downlink data transmission through the unlicensed band. When the base station 110 wants to occupy the unlicensed band for a long time, the LBT may be performed between the maximum channel occupation time and the other maximum channel occupation time. For another example, before transmitting uplink data, the first terminal 120 may perform LBT to check whether a neighboring node of the first terminal 120 occupies the channel.

Even if the base station or the terminal performs LBT before downlink transmission or uplink transmission, channel occupation by other nodes may occur. Since the downlink transmission or the uplink transmission is performed in subframe units, a difference between the start time (or end time) of the LBT and the time of the subframe boundary may occur. That is, channel occupancy by other nodes may occur before and after performing LBT due to the limitation of the resource structure. 2 to 3, the configuration of the base station 110 and the configuration of the first terminal 120 (or the second terminal 130, the third terminal 140) for preventing the channel occupation by other nodes other than the LBT is described, respectively.

2 illustrates a configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure. The configurations illustrated in FIG. 2 may be understood as configurations of the first terminal 120 . '… wealth', '… The term 'group' means a unit for processing at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. The description of the terminal has been described with reference to the first terminal 120, but is not limited thereto, and is also applicable to the second terminal 130 and the third terminal 140.

Referring to FIG. 2 , the first terminal includes a memory 210 , a transceiver 220 , and a processor 230 .

The memory 210 stores data such as a basic program, an application program, and setting information for the operation of the terminal. The memory 210 may be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the memory 210 provides stored data according to the request of the processor 230 . According to an embodiment, the memory 210 may store message information related to transmission/reception of a reservation signal with a base station. For example, the first terminal may receive information about transmission and reception of a reservation signal from the base station before completion of downlink transmission, and store it in the memory 210 . Here, the message about the reservation signal, the transmission subject of the reservation signal, the time of transmission and reception of the next reservation signal, the number of transmission and reception of the reservation signal before the completion of the downlink currently being transmitted, can include various information such as accurate timing for performing LBT have.

The transceiver 220 performs functions for transmitting and receiving signals through a wireless channel. For example, the transceiver 220 performs a conversion function between a baseband signal and a bit stream according to the physical layer standard of the system. For example, when transmitting data, the transceiver 220 generates complex symbols by encoding and modulating the transmitted bit stream. In addition, when receiving data, the communication unit 210 restores the received bit stream by demodulating and decoding the baseband signal. In addition, the transceiver 220 up-converts the baseband signal to a radio frequency (RF) band signal, transmits it through the antenna, and down-converts the RF band signal received through the antenna to a baseband signal. do. For example, the transceiver 220 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like.

Also, the transceiver 220 may include a plurality of transmission/reception paths. Furthermore, the transceiver 220 may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the transceiver 220 may include a digital circuit and an analog circuit (eg, a radio frequency integrated circuit (RFIC)). Here, the digital circuit and the analog circuit may be implemented as one package. In addition, the transceiver 220 may include multiple RF chains. Furthermore, the transceiver 220 may perform beamforming.

As described above, the transceiver 220 transmits and receives signals. Accordingly, all or part of the transceiver 220 may be referred to as a 'transmitter unit', a 'receiver unit', or a 'communication unit'. In addition, in the following description, transmission and reception performed through a wireless channel are used in the meaning of including the processing as described above by the transceiver 220 . According to various embodiments, the transceiver 220 may include a Wi-Fi radio frequency (RF) module 222 . The Wi-Fi RF module 222 transmits a signal including information on a transmission rate (PHY rate) of a physical layer and length of a frame in a Wi-Fi preamble. That is, the Wi-Fi RF module 222 may be a module having at least one RF chain for generating and transmitting a Wi-Fi signal. Here, the transmission rate and Wi-Fi frame length information of the physical layer included in the Wi-Fi preamble may be used to predict a transmission end time of a Wi-Fi frame currently being transmitted by an adjacent Wi-Fi node.

The processor 230 controls overall operations of the first terminal. For example, the processor 230 transmits and receives signals via the transceiver 220 . In addition, the processor 230 writes data to and reads data from the memory 210 . In addition, the processor 230 may perform functions of a protocol stack required by a communication standard. To this end, the processor 230 may include at least one processor or microprocessor, or may be a part of the processor. Also, a part of the transceiver 220 and the processor 230 may be referred to as a communication processor (CP). In particular, according to various embodiments, the processor 230 controls the first terminal to generate a transport block according to control information received from the base station, and to map the generated transport block to the allocated uplink resource. For example, the processor 230 may control the first terminal to perform operations according to various embodiments to be described later. According to an embodiment, the processor 230 may further include an LBT module 232 . An LBT operation according to various embodiments may be performed through the LBT module 232 . The LBT module 232 controls the terminal to determine whether the channel is empty through channel sensing, and if the channel is empty, occupies the corresponding channel during the channel occupation period to perform communication and operate in a manner that performs channel sensing again.

3 illustrates a configuration of a base station in a wireless communication system according to various embodiments of the present disclosure. The configurations illustrated in FIG. 3 may be understood as configurations of the base station 110 . '… wealth', '… The term 'group' means a unit for processing at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

Referring to FIG. 3 , the base station includes a memory 310 , a transceiver 320 , and a processor 330 .

The memory 310 stores data such as a basic program, an application program, and setting information for the operation of the base station. The memory 310 may be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the memory 310 provides stored data according to the request of the processor 330 .

The transceiver 320 performs functions for transmitting and receiving signals through a wireless channel. For example, the transceiver 320 performs a conversion function between a baseband signal and a bit stream according to a physical layer standard of a system. For example, when transmitting data, the transceiver 320 generates complex symbols by encoding and modulating the transmitted bit stream. In addition, when receiving data, the transceiver 320 restores the received bit stream by demodulating and decoding the baseband signal. In addition, the transceiver 320 up-converts the baseband signal into a radio frequency (RF) band signal, transmits it through the antenna, and down-converts the RF band signal received through the antenna into a baseband signal. To this end, the transceiver 320 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC.

Also, the transceiver 320 may include a plurality of transmit/receive paths. Furthermore, the transceiver 320 may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the transceiver 320 may be composed of a digital unit and an analog unit, and the analog unit may be composed of a plurality of sub-units according to operating power, operating frequency, etc. can

The transceiver 320 transmits and receives signals as described above. Accordingly, all or a part of the transceiver 320 may be referred to as a 'transmitter', 'receiver' or 'communicator'. In addition, in the following description, transmission and reception performed through a wireless channel are used in a meaning including the processing as described above by the transceiver 320 . According to various embodiments, the transceiver 320 may include a Wi-Fi radio frequency (RF) module 322 . The Wi-Fi RF module 322 transmits a signal including information on the transmission rate of the physical layer and the length of the frame in the Wi-Fi preamble. That is, the Wi-Fi RF module 322 may be a module including at least one RF chain for generating and transmitting a Wi-Fi preamble signal. Here, the transmission rate and Wi-Fi frame length information of the physical layer included in the Wi-Fi preamble may be used to predict the transmission end time of the Wi-Fi frame currently being transmitted by the adjacent Wi-Fi node.

The processor 330 controls overall operations of the base station. For example, the processor 330 transmits and receives signals via the transceiver 320 . In addition, the processor 330 writes data to and reads data from the memory 310 . In addition, the processor 330 may perform functions of a protocol stack required by a communication standard. To this end, the processor 330 may include at least one control unit. According to various embodiments, the processor 330 may include a scheduler. The scheduler may allocate resources for downlink transmission. Also, the scheduler may allocate resources for uplink transmission. The scheduler is an instruction set or code stored in the memory 310, at least temporarily resident in the processor 330, a storage space storing instructions/code or instructions/code, or a part of circuitry constituting the processor 330. can For example, the processor 330 may control the base station to perform operations according to various embodiments to be described later.

According to various embodiments, the processor 330 may include a message generator 332 . The message generator 332 may generate a message for notifying the information about the reservation signal to the first terminal. Specifically, the information about the reservation signal included in the message includes the transmission subject of the reservation signal, the transmission/reception time of the next reservation signal, the number of transmission/reception of the reservation signal before completion of the downlink currently being transmitted, and the exact timing for performing LBT. may contain information. Accordingly, the first terminal receives a message including information about the reservation signal, and may determine the timing for the operation, such as performing LBT and transmission of the reservation signal according to the information.

Hereinafter, a procedure for occupying a channel between transmissions (eg, between downlink transmission and uplink transmission) will be described with reference to FIGS. 4 to 11 . Through FIGS. 4 to 6, channel occupation between transmissions of the terminal, through FIGS. 7 to 9, channel occupation between transmissions of the base station, and through FIGS. 10 to 12, examples for channel occupation between transmissions of the base station and the terminal are described do.

Channel Occupation Between Transports

4 illustrates an operation flow of a terminal for occupying a channel in a wireless communication system according to various embodiments of the present disclosure. 4 illustrates an operation method of the first terminal 120 .

Referring to FIG. 4 , in step 401, the first terminal may receive downlink data. That is, the first terminal may receive downlink data from the base station through the channel currently occupied by the first terminal. According to an embodiment, the first terminal is an LAA terminal that performs LBT for operation in an unlicensed band. can The first terminal may not receive downlink data up to the boundary of the downlink subframe. That is, the time at which the first terminal terminates the downlink data reception may not coincide with the downlink subframe boundary. For example, downlink data reception may be terminated at a time point earlier than the downlink subframe boundary by one symbol length. As another example, the last subframe of downlink transmission may be a subframe referred to as an ending partial subframe. In the case of a partial end subframe, the downlink data reception of the first terminal may be terminated earlier by a length greater than one symbol. The first terminal may have a predetermined time period after the end of downlink data reception and before uplink transmission.

In step 403, the first terminal may perform an LBT operation for uplink transmission, that is, the first terminal may perform an LBT operation to occupy a channel for uplink transmission following downlink transmission. In order to perform the LBT operation, the first terminal may determine whether the channel is idle during the CCA slot. As an example, the first terminal may perform LBT for 25us through LBT of category 2 (a method that does not perform random backoff) defined in 3GPP. Accordingly, the first terminal may determine whether the channel is occupied by another node for 25 us from the time when downlink data reception is terminated.

In step 405, the first terminal may transmit the first reservation signal based on the LBT end time and subframe boundary. That is, the first terminal may transmit the first reservation signal during the period from the time of terminating the LBT operation to the time of the subframe boundary. According to various embodiments, the LBT end time by the first terminal may precede the subframe boundary. Here, the subframe boundary may indicate a subframe starting point at which the next transmission (eg, uplink transmission) to be performed by the first terminal is started. For example, when the first terminal performs the LBT operation of category 2 for uplink transmission, the LBT performance interval is 25us, and the length of one OFDM symbol is 71.3us. Therefore, when the first terminal performs LBT immediately after terminating downlink data reception, from the LBT end time to the subframe boundary time is 46.3us. Considering that the LBT execution time of category 2 is 25us, another node (eg, an access point (AP) of a wireless local area network (WLAN)) may occupy a channel within 46.3us. Since the first terminal can perform uplink transmission only after the subframe boundary in order to synchronize the time, the time from the end of the LBT to the subframe boundary is wasted meaninglessly. Accordingly, the first terminal may prevent the channel from being occupied by other nodes and transmit the first reservation signal for guaranteeing the occupancy of the channel for uplink transmission. Here, the reservation signal may be referred to as a signal for occupying a channel, but the present disclosure is not limited thereto. The reservation signal may be replaced with other terms having technically equivalent meanings, such as an initial signal, a signal for channel protection, and a jamming signal. According to another embodiment, the reservation signal may include a dummy signal or a Wi-Fi preamble signal. That is, the first terminal can prevent the occupancy of the channel by other nodes by transmitting a reservation signal during the period from the LBT end time to the subframe boundary time. As an example, when the reservation signal is a dummy signal, another node performing LBT may determine that the current channel is occupied by another node. As another example, if the reservation signal is a Wi-Fi preamble signal, another node performing LBT The node may not only determine that the channel is occupied, but may additionally acquire information on the end time of the Wi-Fi frame based on the transmission rate of the physical layer and the length information of the Wi-Fi frame included in the preamble. In this case, since the other node does not transmit a signal until the end of the corresponding Wi-Fi frame, the channel occupation of the first terminal may be additionally protected.

On the other hand, when the LBT end time coincides with the downlink subframe boundary, of course, the first terminal can perform uplink transmission immediately after the end of the LBT. The first terminal may not transmit the first reservation signal.

In step 407, the first terminal may transmit uplink data based on the subframe boundary. That is, the first terminal may transmit the first reservation signal until the subframe boundary time, and when the subframe boundary time is reached, the first terminal may transmit uplink data. The first terminal may synchronize time in scheduling-based uplink transmission by transmitting uplink data based on the subframe boundary.

As described above, the first terminal may transmit a reservation signal for preventing channel occupation by other nodes. Hereinafter, an example of a subframe corresponding to a specific operation flow of the first terminal is shown through FIGS. 5A and 5B.

5A illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 5A , the base station 501 may correspond to the base station 110 of FIG. 1 , the first terminal 503 may correspond to the first terminal 120 of FIG. 1 , and the second terminal 505 may correspond to the second terminal 130 of FIG. 1 . may correspond to each. The second terminal 505 illustrated in FIG. 5A exemplifies a neighboring node different from that of the first terminal 503 .

The time axis 510 represents a flow of time when the base station 501 performs signaling. A situation in which the base station 501 transmits downlink data to the first terminal 503 through the time axis 510 will be described. Specifically, the base station 501 may transmit downlink data through the channel occupied by the first terminal 503 . The last subframe of downlink transmission is shown as section 540. The section 540 corresponding to the last subframe includes a section 541 in which downlink data is transmitted. The length of the section 541 may be determined according to the type of the last subframe of the downlink. The last subframe of the downlink may be a full subframe. The entire subframe means a subframe having a length of 1 ms. The entire subframe may have the same length as other subframes in the frame.

For uplink transmission, the first terminal 503 may perform LBT. After the last subframe of the downlink, the first terminal 503 may start uplink transmission. Therefore, the base station 501 may transmit downlink data except for the last OFDM symbol of the last subframe for the LBT operation of the first terminal 503. Based on the LTE communication system, since one symbol has a time interval of 71.3us, interval 541 may correspond to a time interval for 13 symbols. The interval 543 may correspond to a time interval for one symbol. Accordingly, the interval 543 has an interval of 71.3 us. The base station 501 may transmit downlink data to the first terminal 503 during section 541. The first terminal 503 may detect when the reception of downlink data ends. According to various embodiments, the first terminal 503 may obtain information on the type of the last subframe and the downlink data transmission end time in advance through signaling with the base station 501 . The first UE 503 may perform LBT in the last OFDM symbol of the last subframe.

The time axis 520 represents a flow of time when the first terminal 503 performs signaling. Through the time axis 520, a situation in which the first terminal 503 performs LBT and occupies a channel in order to transmit uplink data is described. The first terminal 503 may perform an LBT operation in response to detection of the end of downlink data reception. For example, the first terminal 503 may perform the LBT operation of category 2 for 25 us. When the reception of downlink data from the base station 501 is terminated, the first terminal 503 may perform LBT during section 545.

The first terminal 503 may determine whether the channel is in an idle state. The first terminal 503 may transmit the dummy reservation signal 549 during the period 547 when the channel is in an idle state, that is, when the channel is not occupied by another node such as the second terminal 505 . A section 547 indicates a section in which the first terminal 503 transmits a reservation signal. Section 547 may correspond to a section before the subframe boundary after the end of the LBT of the first terminal 503. The first terminal 503 may transmit a signal for preventing channel occupation by other nodes such as the second terminal 505 during the period 547. The length of the section 543 is 71.3us corresponding to the length of one OFDM symbol. Therefore, the interval 547 may be 46.3us of the time excluding the 25us of the LBT execution time of the first terminal 503.

According to various embodiments, the reservation signal transmitted by the first terminal 503 may be a dummy reservation signal 549 . The first terminal 503 may broadcast the dummy reservation signal 549 to another node such as the second terminal 505 located within the coverage area. According to various embodiments, the first terminal 503 may transmit a reservation signal of a shorter or longer time than the time excluding the LBT execution time in one symbol in consideration of the propagation delay for accurate time synchronization. . When the second terminal 505 is located within the coverage of the first terminal 503, the second terminal 505 may receive a dummy reservation signal 549 from the first terminal 503. The second terminal 505 may determine that the current channel is occupied by the first terminal 503 . The first terminal 503 may inform all nodes within coverage for performing channel sensing that the current channel is not in an idle state through the dummy reservation signal 549 .

The time axis 530 represents the flow of the second terminal 505 with respect to time. The second terminal 505 exemplifies a node performing communication through an unlicensed band. The second terminal 505 may perform LBT in section 543. Interval 543 may include interval 545 or interval 547 . The second terminal 505 may perform LBT in section 547. The second terminal 505 may detect the dummy reservation signal 549 transmitted by the first terminal 503 . The second terminal 505 may detect that the channel is occupied by another node, that is, the first terminal 503 .

The second terminal 505 may perform LBT in section 545. If the second terminal 505 does not perform LBT immediately after the end of section 541, it cannot occupy the channel. The first terminal 503 may perform LBT for a time of 25 us immediately after the end of section 541, and immediately transmit a dummy reservation signal 549. Therefore, the second terminal 505 may receive the dummy reservation signal 549 from the first terminal 503 before the completion of the LBT operation of 25us. Accordingly, the second terminal 505 may determine that the channel is occupied by another node (eg, the first terminal 503). The second terminal 505 may perform LBT for data transmission after a predetermined time has elapsed. Since the second terminal 505 does not know exactly the end time of the downlink data transmission of the base station 501, the probability that the second terminal 505 occupies the channel by performing the LBT at the same time as the first terminal 503 is low. When the first terminal 503 transmits the reservation signal, the occupation of the channel of the first terminal 503 may be guaranteed.

As described above, the terminal (eg, terminal 1 503) transmits a reservation signal (eg, dummy reservation signal 549) up to the subframe boundary to prevent occupation of the channel by other nodes (eg, terminal 2 505) and , can occupy the channel.

5B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 5B , descriptions of the same section as the section shown in FIG. 5A and the same or similar operation as the section shown in FIG. 5A will be omitted.

In section 547, the first terminal 503 may transmit the Wi-Fi preamble reservation signal 551 instead of the dummy reservation signal 549 of FIG. 5A. The Wi-Fi preamble reservation signal 551 is a signal generated by the Wi-Fi RF module included in the transceiver of the first terminal 503 . The Wi-Fi preamble may include information on a transmission speed of a physical layer and a Wi-Fi frame length. A neighboring node, for example, the second terminal 505 may receive the Wi-Fi preamble reservation signal 551 . The second terminal 505 may determine a time period in which the current Wi-Fi frame is transmitted by obtaining information on the transmission rate and the Wi-Fi frame length included in the Wi-Fi preamble. For example, the second terminal 505 may determine a time period in which the Wi-Fi frame is transmitted by performing a division operation on the Wi-Fi frame length by the transmission rate. According to various embodiments, the Wi-Fi preamble reservation signal 551 transmitted from the first terminal 503 may notify not only the adjacent Wi-Fi node but also the adjacent node other than the Wi-Fi node of the idle state of the channel. Specifically, by receiving the Wi-Fi preamble reservation signal 551, the adjacent Wi-Fi node may know that the current channel is occupied by another node. In addition, the adjacent Wi-Fi node may know the transmission end time of the Wi-Fi frame based on the transmission rate and Wi-Fi frame length information. A neighboring node other than the Wi-Fi node may perform channel sensing. Accordingly, a neighboring node other than the Wi-Fi node may not be able to obtain information included in the Wi-Fi preamble. However, a neighboring node other than the Wi-Fi node may acquire information on the idle state of the channel through channel sensing. That is, by transmitting the Wi-Fi preamble reservation signal 551, the first terminal 503 not only prevents channel occupancy by an adjacent node like the dummy reservation signal 549, but also suppresses transmission by the adjacent Wi-Fi node, so that the uplink of the first terminal 503 Transmission can be further protected.

A section 553 indicates an uplink transmission section protected by the Wi-Fi preamble reservation signal 551. In the Wi-Fi communication system, L-SIG transmission opportunity protection (legacy signal transmission opportunity protection, hereinafter, L-SIG protection) technology is used to prevent signal interference. The Wi-Fi node (eg, the second terminal 505) performing the L-SIG protection operation does not transmit a signal until the Wi-Fi frame being transmitted from the currently adjacent node (eg, the first terminal 503) ends, thereby inter-signal interference can prevent Accordingly, since the second terminal 505 does not transmit a signal to the base station 501 according to the L-SIG protection operation until the end of the currently transmitted Wi-Fi frame, the uplink transmission between the base station 501 and the first terminal 503 can be additionally protected. .

6A illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 6A , a base station 601 may correspond to a base station 110 of FIG. 1 , a first terminal 603 may correspond to a first terminal 120 of FIG. 1 , and a second terminal 605 may correspond to the second terminal 130 of FIG. 1 . may correspond to each. The second terminal 605 illustrated in FIG. 6A exemplifies a neighboring node different from that of the first terminal 603 .

The time axis 610 represents a flow of time when the base station 601 performs signaling. A situation in which the base station 601 transmits downlink data to the first terminal 603 through the time axis 610 will be described. Specifically, the base station 601 may transmit downlink data through the channel occupied by the first terminal 503 .

A section 641 indicates a downlink data transmission section by the base station 601. That is, the base station 601 may complete downlink data transmission before the subframe boundary of the last subframe of downlink transmission. Here, the length of the section 641 may be determined according to the type of the last subframe in the downlink. According to various embodiments, the last subframe of downlink transmission may be a subframe in which downlink data transmission ends earlier than the entire subframe of FIG. 5A. That is, the section 641 may be a section corresponding to a smaller number than 13 symbols based on the LTE communication system. For example, the last subframe may be a subframe referred to as an ending partial subframe. For another example, the last subframe may be a subframe for short transmission time interval (TTI) transmission. As another example, the last subframe may be a subframe for transmitting a sounding reference signal (SRS). That is, the downlink data transmission may be terminated earlier than the transmission except for the last OFDM symbol, unlike FIG. 5A.

The time axis 620 represents the flow of time for the operation of the first terminal 603 . The first terminal 603 receives downlink data from the base station 601 . Upon completion of downlink data reception, the first terminal 603 may perform LBT for occupying a channel for uplink transmission. When the channel is idle according to the LBT performance, the first terminal 603 may occupy the channel, and may transmit uplink data to the base station 601. However, the first terminal 603 may transmit uplink data after the subframe boundary. Therefore, the first terminal 603 needs to prevent the idle state of the channel from the LBT completion time to the subframe boundary.

A period 643 indicates a time period from the end of downlink data transmission to the subframe boundary of the last subframe of the downlink. That is, section 643 is a section from when downlink data transmission between the base station 601 and the first terminal 603 ends and uplink transmission starts. The period 643 may be determined according to the type of the last subframe of downlink transmission. When the last subframe of downlink transmission is a partial end subframe, the period 643 may have a value greater than one symbol length of 71.3us. The length of the section 643 may be determined according to the size of downlink data transmitted to the first terminal 603 and the length of the allocated downlink frame.

Section 645 corresponds to a section in which the first terminal 603 performs LBT. That is, the first terminal 603 may perform LBT for the period 645 in order to occupy the channel for uplink transmission. The first terminal 603 may perform the LBT operation of category 2 for 25 us. Accordingly, the section 645 may have a length of 25 us. According to various embodiments, the first terminal 603 may obtain information on the type of the last subframe and the end time of downlink data transmission in advance through signaling with the base station 601 . The first terminal 603 may perform LBT at the time of completion of downlink data transmission of the partial end subframe.

A section 647 indicates a section in which the first terminal 603 transmits the dummy reservation signal 649. The first terminal 603 may transmit the dummy reservation signal 649 to prevent channel occupation by another node (eg, the second terminal 605 ). After the end of the LBT, the first terminal 603 may transmit the dummy reservation signal 649 through the section before the uplink transmission. That is, the first terminal 603 transmits the dummy reservation signal 649 from the LBT end time to the subframe boundary of downlink transmission. Here, it goes without saying that the subframe boundary of downlink transmission and the uplink subframe boundary coincide. The first terminal 603 may check the idle state of the channel through LBT performance during the period 645. However, the first terminal 603 may transmit uplink data after the subframe boundary in order to synchronize the scheduling-based uplink time. If the first terminal 603 does not transmit a reservation signal until the subframe boundary after the end of the LBT, the channel may be in an idle state for the period 647. When the last subframe of downlink transmission is a partial end subframe, the length of the section 643 corresponding to the idle state of the channel becomes larger than one symbol, whereas the LBT operation execution time is fixed to 25us, so the dummy reservation signal 649 is The length of the transmission interval 647 may be greater than the length of one OFDM symbol. The first terminal 603 may broadcast the dummy reservation signal 649 to all nodes within coverage in order to prevent channel occupation by neighboring nodes such as the second terminal 605 . According to various embodiments, the first terminal 603 may transmit a reservation signal of a shorter or longer time than the time excluding the LBT execution time in consideration of the propagation delay for accurate time synchronization. An adjacent node such as the second terminal 605 may determine that the current channel is occupied by another node (eg, the first terminal 603 ) by receiving the dummy reservation signal 649 . As described above, since downlink transmission is terminated earlier than the defined subframe length, the idle time of the channel may be lengthened. In spite of the long channel idle time, the channel occupation of the first terminal 603 can be protected by transmitting the reservation signal.

6B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 6B , descriptions of the same section as the section shown in FIG. 6A and the same or similar operation as the section shown in FIG. 6A will be omitted.

In section 647, the first terminal 603 may transmit the Wi-Fi preamble reservation signal 651 instead of the dummy reservation signal of FIG. 6A . As described above, the Wi-Fi preamble includes information on the transmission rate of the physical layer and the Wi-Fi frame length. An adjacent node, for example, the second terminal 605 may receive the Wi-Fi preamble reservation signal 649 from the first terminal 603 while performing LBT for channel occupation. The second terminal 605 may determine that the current channel is occupied by a neighboring node, that is, the first terminal 603 . Therefore, the second terminal 605 may perform LBT for data transmission after a certain time has elapsed.

Interval 653 indicates the L-SIG guard interval by the second terminal 605. The second terminal 605 may receive the Wi-Fi preamble reservation signal 649 from the first terminal 603 during section 647. The second terminal 505 obtains information on a transmission rate and a Wi-Fi frame length included in the received preamble. The second terminal 605 may know the duration of the Wi-Fi frame and the end time of the Wi-Fi frame by performing a division operation on the Wi-Fi frame length by the transmission rate. Here, the determined Wi-Fi frame duration may correspond to section 653. The second terminal 605 may perform the L-SIG protection operation for the determined duration of the WiFi frame from the point in time when the transmission of the WiFi preamble reservation signal 651 from the first terminal 603 is completed. That is, in order to protect uplink transmission between the base station 601 and the first terminal 603, the second terminal 605 may prevent inter-signal interference by not transmitting a signal during the period 653. Accordingly, channel occupation of the first terminal 603 can be protected from other nodes.

7 illustrates an operation flow of a base station for channel occupation in a wireless communication system according to various embodiments of the present disclosure. 7 illustrates an operating method of the base station 110 .

Referring to FIG. 7 , in step 701 , the base station may transmit downlink data. That is, the base station may transmit data through downlink transmission with the first terminal. The base station may complete data transmission before the boundary of the last subframe in consideration of the LBT execution time of the first terminal for uplink after downlink. That is, the subframe boundary time point and the data transmission completion time point may be different. According to an embodiment, the base station may transmit data except for the last symbol of the last subframe in consideration of the LBT execution time of the first terminal. According to another embodiment, the base station may complete data transmission earlier by a length greater than one symbol. In this case, the last subframe may be referred to as an ending partial subframe.

In step 703, the base station may transmit the first reservation signal based on the transmission completion time, a certain period, and the subframe boundary. That is, the base station may determine the length of the interval for transmitting the first reservation signal and transmit the signal in consideration of the completion time of the downlink data transmission, the LBT execution time of the first terminal, and the subframe boundary. According to an embodiment, the base station may transmit the first reservation signal during the remaining time except for the time required for the first terminal to perform LBT. For example, when the last subframe of downlink transmission is all subframes, one section of the last symbol may be excluded from downlink data transmission. Therefore, the base station may determine the transmission period of the first reservation signal so that the first terminal starts uplink transmission immediately after performing the LBT. In this case, the base station may transmit the first reservation signal for a time of 46.3us immediately after the downlink data transmission is completed. According to another embodiment, the base station may determine the transmission period of the first reservation signal in consideration of the second reservation signal transmitted from the first terminal. For example, the first terminal may receive the first reservation signal from the base station, perform LBT, and transmit the second reservation signal. In this case, the first terminal may transmit the second reservation signal from the end of the LBT to the subframe boundary time, and after the transmission of the second reservation signal is completed, the uplink data may be transmitted immediately at the subframe boundary time. Accordingly, the base station may flexibly transmit the first reservation signal according to the transmission time of the LBT execution time and the second reservation signal of the first terminal.

In step 705, the base station may receive uplink data based on the subframe boundary. That is, since the first terminal transmits uplink data based on the subframe boundary, the base station may receive the uplink data from the first terminal according to the subframe boundary.

As described above, the base station may transmit a reservation signal for preventing channel occupation by other nodes. Hereinafter, an example of a subframe corresponding to a specific operation flow of the base station is shown through FIGS. 8A to 8B.

8A illustrates an example of a subframe for transmission of a reservation signal between transmissions of a base station in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 8A , the base station 801 may correspond to the base station 110 of FIG. 1 , the first terminal 803 may correspond to the first terminal 120 of FIG. 1 , and the second terminal 805 may correspond to the second terminal 130 of FIG. 1 . may correspond to each. The second terminal 805 shown in FIG. 8 exemplifies a neighboring node different from that of the first terminal 803 .

The time axis 810 represents a flow of time when the base station 801 performs signaling. A situation in which the base station 801 transmits downlink data to the first terminal 803 through the time axis 810 will be described.

The base station 801 may transmit downlink data through the channel occupied by the first terminal 803 . The last subframe of downlink transmission is shown as an interval 840. The section 840 corresponding to the last subframe includes a section 841 in which downlink data is transmitted. The length of the section 841 may be determined according to the type of the last subframe of the downlink. The last subframe of the downlink may be an entire subframe. Section 843 except for the section in which downlink data is transmitted in section 840 may correspond to the length of the last one OFDM symbol.

The base station 801 may transmit a reservation signal after transmission of downlink data. Since the base station 801 knows when the downlink data transmission is complete, it can transmit the reservation signal immediately after the downlink data transmission during section 845. The reservation signal transmitted by the base station 801 may be a dummy reservation signal 849 . According to an embodiment, the base station 801 may determine the interval 845 so that the first terminal 803 can transmit uplink data immediately after performing the LBT. For example, based on the LTE communication system, the section 843 corresponding to the length of one symbol is 71.3us. The base station 801 may determine the length of the section 845 in which the dummy reservation signal 849 is transmitted as 46.3us excluding the time of 25us, which is the category 2 LBT execution time performed by the first terminal.

The time axis 820 represents a flow of time when the first terminal 803 performs signaling. A situation in which the first terminal 803 performs LBT and transmits uplink data through the time axis 820 will be described. The first terminal 803 may receive downlink data from the base station 801 during section 841. The first terminal 803 may receive the dummy reservation signal 849 from the base station 801 during the period 845. The dummy reservation signal 849 is a signal that the base station 801 broadcasts to all nodes within coverage. According to various embodiments, the base station 801 may transmit a reservation signal of a shorter or longer time than the time excluding the LBT execution time in consideration of a propagation delay for accurate time synchronization.

In section 847, when the reception of the dummy reservation signal 849 ends, the first terminal 803 may immediately perform LBT for uplink transmission. The first terminal 803 may perform the LBT operation of category 2 for 25 us. Since the LBT end time coincides with the subframe boundary, the first terminal 803 may transmit uplink data to the base station 801 immediately after the LBT ends. As described above, the terminal (eg, terminal 1 803) transmits a reservation signal (eg, dummy reservation signal 849) up to the subframe boundary to prevent occupation of the channel by other nodes (eg, terminal 2 805) and , can occupy the channel.

8B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 8B , descriptions of the same section as the section shown in FIG. 8A and the same or similar operation as the section shown in FIG. 8A will be omitted.

In section 845, the base station 801 may transmit the Wi-Fi preamble reservation signal 851 instead of the dummy reservation signal 849 of FIG. 8A. As described above, the Wi-Fi preamble includes information on the transmission rate of the physical layer and the Wi-Fi frame length. The base station 801 may broadcast the Wi-Fi preamble reservation signal 851 to all nodes within coverage.

A period 853 indicates an L-SIG guard period performed by the second terminal 805. The second terminal 805 may receive the Wi-Fi preamble reservation signal 851 from the base station 801 during section 845. The second terminal 805 obtains information on a transmission rate and a Wi-Fi frame length included in the received preamble. The second terminal 805 may determine the Wi-Fi frame duration by performing a division operation on the Wi-Fi frame length by the transmission rate. The determined Wi-Fi frame duration may correspond to the length of the section 853. The second terminal 805 may perform the L-SIG protection operation during the Wi-Fi frame duration determined from the time when the reservation signal transmission from the base station 801 is completed. That is, in order to protect uplink transmission between the base station 801 and the first terminal 803, the second terminal 805 may prevent inter-signal interference by not transmitting a signal during the period 853. Accordingly, channel occupation of the first terminal 803 can be protected from other nodes.

9A illustrates an example of a subframe for transmission of a reservation signal between transmissions of a base station in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 9A , the base station 901 may correspond to the base station 110 of FIG. 1 , the first terminal 903 may correspond to the first terminal 120 of FIG. 1 , and the second terminal 905 may correspond to the second terminal 130 of FIG. 1 . may correspond to each. The second terminal 905 illustrated in FIG. 9A exemplifies a neighboring node different from that of the first terminal 903 .

The time axis 910 represents a flow of time when the base station 901 performs signaling. A situation in which the base station 901 transmits downlink data and a reservation signal to the first terminal 903 through the time axis 910 will be described. The base station 901 transmits downlink data through the channel occupied by the first terminal 903. Section 940 shows the last subframe of downlink transmission for data transmission. The last subframe of downlink data transmission corresponding to section 941 may be a partial end subframe. Hereinafter, a detailed description of the partial end subframe corresponds to FIG. 6A .

In section 945, the base station 901 may transmit a dummy reservation signal 949. Since the base station 901 is the subject of downlink data transmission, it can know the completion time of data transmission. The base station 901 may continuously transmit the dummy reservation signal 949 to downlink data. The base station 901 may transmit the dummy reservation signal 949 to all nodes within its coverage during the period 945. According to various embodiments, the base station 901 may transmit a reservation signal of a shorter or longer time than the time excluding the LBT execution time in consideration of the propagation delay for accurate time synchronization. The dummy reservation signal 949 may inform all nodes that perform channel sensing within the coverage of the base station 901 that the current channel is not in an idle state.

The time axis 920 represents a flow of time during which the first terminal 903 performs an operation. A situation in which the first terminal 903 performs LBT and transmits uplink data through the time axis 920 will be described. The first terminal 903 may perform LBT for uplink transmission during section 947. When the reception of the dummy reservation signal 949 from the base station 901 is finished, the first terminal 903 may perform LBT immediately. The first terminal 903 may perform the LBT operation of category 2 for 25 us. According to various embodiments of the present disclosure, the first terminal 903 may previously obtain information on the type of the last subframe and the transmission end time of the dummy reservation signal 949 through signaling with the base station 901 . The first terminal 903 may perform LBT at the time when the transmission of the dummy reservation signal 949 is completed.

The second terminal 905 may perform LBT after completion of downlink data transmission between the base station 901 and the first terminal 903, that is, in section 945. The second terminal 905 may receive the dummy reservation signal 949 from the base station 901 during the LBT operation, and determine that the current channel is occupied by another node (eg, the first terminal 903). The second terminal 905 may perform LBT for data transmission after a certain time has elapsed. Accordingly, as the base station 901 transmits the reservation signal, the occupation of the channel of the first terminal 903 can be guaranteed.

9B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 9B , descriptions of the same section as the section shown in FIG. 9A and the same or similar operation as the section shown in FIG. 9A will be omitted.

In section 945, the base station 901 may transmit a Wi-Fi preamble reservation signal 951. As described above, the Wi-Fi preamble includes information on the transmission rate of the physical layer and the Wi-Fi frame length. The base station 901 may broadcast the Wi-Fi preamble reservation signal 951 to all nodes within coverage.

Interval 953 indicates the L-SIG guard interval of the second terminal 905. The second terminal 905 may receive the Wi-Fi preamble reservation signal 951 from the base station 901 during section 945. The second terminal 905 may acquire information on a transmission rate and a Wi-Fi frame length included in the received preamble. The second terminal 905 may determine the frame duration by performing a division operation on the Wi-Fi frame length by the transmission rate. The determined Wi-Fi frame duration may correspond to the length of the section 953. The second terminal 905 may perform the L-SIG protection operation for the determined Wi-Fi frame duration from the point in time when the transmission of the Wi-Fi reservation signal 951 from the base station 901 is completed. In order to protect uplink transmission between the base station 901 and the first terminal 903, the second terminal 905 may prevent inter-signal interference by not transmitting a signal during the period 953. Accordingly, uplink transmission between the base station 901 and the first terminal 903 can be additionally protected.

10A illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 10A , the base station 1001 may correspond to the base station 110 of FIG. 1 , and the first terminal 1003, the second terminal 1005, and the third terminal 1007 are the first terminal 120, the second terminal 130, and the second terminal of FIG. 1, respectively. 3 may correspond to terminal 140 .

The time axis 1010 represents a flow of time when the base station 1001 performs signaling. A situation in which the base station 1001 transmits downlink data to the first terminal 1003 through the time axis 1010 will be described. The base station 1001 may transmit downlink data through the channel occupied by the first terminal 1003 . The last subframe of downlink transmission is shown as interval 1050. The period 1051 is a period in which downlink data is transmitted and may be determined according to the type of the last subframe of the downlink transmission. The period 1050 may be an entire subframe, and the period 1053 may be a period of one symbol according to the LTE communication system. That is, the base station 1001 may transmit downlink data except for one last symbol of the last subframe for the LBT operation of the first terminal 1003. Accordingly, the period 1051 may be a period corresponding to 13 OFDM symbols.

A section 1055 indicates a section in which the base station 1001 transmits the dummy reservation signal 1061. According to various embodiments, the base station 1001 may transmit a reservation signal of a shorter or longer time than the time excluding the LBT execution time in consideration of a propagation delay for accurate time synchronization. The dummy reservation signal 1061 may be broadcast to all nodes within the coverage of the base station 1001 . An adjacent node performing channel sensing (eg, terminal 2 1005) may determine that the channel is currently occupied by another node (eg, terminal 1 1003) by receiving the dummy reservation signal 1061. The section 1055 in which the dummy reservation signal 1061 is transmitted may be determined in consideration of the length of the dummy reservation signal 1063 transmitted from the first terminal 1003, and the LBT execution time performed by the first terminal 1003. For example, 1061 of the dummy reservation signal, 1057 of the LBT execution period, and the transmission period of the dummy reservation signal 1063 may be included in one symbol. The base station 1001 may transmit a reservation signal flexibly within a time length of 46.3us excluding the time of 25us required for the first terminal 1003 for LBT operation in 71.3us corresponding to one symbol. An embodiment in which the base station 1001 transmits a reservation signal for a maximum of 46.3us corresponds to FIG. 8, and an embodiment in which the base station 1001 transmits a reservation signal for 0us, that is, does not transmit a reservation signal, corresponds to FIGS. 5 to 6 . Therefore, hereinafter, FIG. 10 will be described based on the case where both the base station 1001 and the first terminal 1003 transmit reservation signals. Accordingly, the base station 1001 may transmit the dummy reservation signal 1061 having a predetermined period within a maximum of 46.3 us.

A time axis 1020 represents a flow of time when the first terminal 1003 performs signaling. A situation in which the first terminal 1003 receives downlink data and a reservation signal from the base station 1001 through the time axis 1020, performs an LBT operation, and transmits a dummy reservation signal will be described. Hereinafter, for convenience of description, a dummy reservation signal 1061 transmitted by the base station 1001 will be described as a first reservation signal, and a dummy reservation signal 1063 transmitted by the first terminal 1003 will be described as a second reservation signal. When the reception of the first reservation signal from the base station 1001 is terminated, the first terminal 1003 may perform an LBT operation. The first terminal 1003 may perform an LBT operation for uplink transmission during the period 1057. The first terminal 1003 may perform an LBT operation immediately after reception of the first reservation signal is completed in order to prevent channel occupation by other nodes.

The first terminal 1003 may transmit the second reservation signal during the period 1059. That is, after performing the LBT, the first terminal 1003 may transmit the dummy reservation signal 1063 until the subframe boundary time. The first terminal 1003 may transmit the second reservation signal to all nodes within the coverage. All nodes within the coverage may determine that the current channel is occupied by another node (eg, the first terminal 1003) by receiving the second reservation signal. Thereafter, the first terminal 1003 may transmit uplink data based on the subframe boundary.

A time axis 1030 and a time axis 1040 represent temporal flows for the second terminal 1005 and the third terminal 1007, respectively. Specifically, although the second terminal 1005 is within the coverage of the base station 1001, it may refer to all nodes existing outside the coverage of the first terminal 1003. The third terminal 1007 is outside the coverage of the base station 1001, but may refer to all nodes existing within the coverage of the first terminal 1003.

The second terminal 1005 may receive the first reservation signal from the base station 1001. The second terminal 1005 may determine that the current channel is occupied by another node through the first reservation signal. The second terminal 1005 may perform LBT for data transmission after a certain time has elapsed. The third terminal 1007 may receive the second reservation signal from the first terminal 1003 . The third terminal 1007 determines that the channel is currently occupied by another node, and after a certain time has elapsed, LBT for data transmission may be performed.

10B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 10B , descriptions of the same section as the section shown in FIG. 10A and the same or similar operation as the section shown in FIG. 10A will be omitted.

In section 1055, the base station 1001 transmits a Wi-Fi preamble reservation signal 1065. As described above, the Wi-Fi preamble transmitted as a reservation signal includes information on the transmission rate of the physical layer and the length of the frame. The second terminal 1005 included in the coverage of the base station 1001 may determine that the current channel is not in an idle state by receiving the Wi-Fi preamble reservation signal 1065. When the second terminal is a Wi-Fi terminal, the second terminal 1005 may predict a Wi-Fi frame transmission completion time based on information included in the preamble. Accordingly, the second terminal may perform the L-SIG protection operation until the frame transmission is completed. Since the third terminal 1007 exists outside the coverage of the base station 1001, it may not receive the Wi-Fi preamble reservation signal 1065.

In section 1059, the first terminal 1003 transmits a Wi-Fi preamble reservation signal 1067. The first terminal 1003 may broadcast the Wi-Fi preamble reservation signal 1067 including information on the transmission speed of the physical layer and the Wi-Fi frame length to all nodes within coverage. Accordingly, the third terminal 1007 may not receive the Wi-Fi preamble reservation signal 1065 from the base station 1001, but may receive the Wi-Fi preamble reservation signal 1067 from the first terminal 1003. The third terminal 1007 may perform an L-SIG protection operation based on information included in the received preamble.

As described above, the base station 1001 or the first terminal 1003 transmits an independent reservation signal, thereby preventing uplink transmission failure due to a node existing outside the coverage.

11A illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 11A , the base station 1101 may correspond to the base station 110 of FIG. 1 . Also, the first terminal 1103 , the second terminal 1105 , and the third terminal 1107 may correspond to the first terminal 120 , the second terminal 130 , and the third terminal 140 of FIG. 1 , respectively.

The time axis 1110 represents a flow with respect to the time during which the base station 1101 performs signaling. A situation in which the base station 1101 transmits downlink data to the first terminal 1103 and receives uplink data through the time axis 1110 will be described.

Section 1151 represents a section in which downlink data is transmitted in the last subframe of downlink transmission. Section 1151 shows a section in which downlink data is transmitted according to the partial end subframe, and section 1153 shows a section corresponding to a length greater than the length of one symbol according to the LTE communication system.

During the period 1155, the base station 1101 transmits the dummy reservation signal 1161. The base station 1101 transmits the dummy reservation signal 1161 to all nodes within coverage. A neighboring node may determine that the current channel is not idle. The second terminal 1105 may receive the dummy reservation signal 1161 from the base station 1101, but the third terminal 1107 may not receive the reservation signal from the base station 1101 because it is out of coverage.

During the period 1159, the first terminal 1103 transmits the dummy reservation signal 1163. The first terminal 1103 transmits a reservation signal to all nodes within coverage. A node adjacent in coverage may determine that the current channel is not idle. The third terminal 1107 may receive the reservation signal from the first terminal 1103, but the second terminal 1105 may not receive the reservation signal from the first terminal 1103 because it exists outside the coverage of the first terminal 1103.

As described above, as the base station 1101 and the first terminal 1103 transmit reservation signals, respectively, it is possible to notify a node existing outside the coverage that the current channel is not in an idle state. Accordingly, by transmitting the reservation signal, it is possible to guarantee the occupation of the channel for uplink transmission of the first terminal.

11B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 11B , descriptions of the same section as the section shown in FIG. 11A and the same or similar operation as the section shown in FIG. 11A will be omitted.

During section 1155, the base station 1101 transmits the Wi-Fi preamble reservation signal 1165. All nodes within the coverage of the base station 1101 determine that the current channel is occupied by another node by receiving the Wi-Fi preamble reservation signal 1165. Adjacent nodes may perform an LBT operation for data transmission after a certain period of time has elapsed. The Wi-Fi node located within the coverage of the base station 1101 may predict the end time of the frame based on information included in the preamble and perform the L-SIG protection operation.

During section 1159, the first terminal 1103 may transmit the Wi-Fi preamble reservation signal 1167. That is, the first terminal 1103 may broadcast the Wi-Fi preamble reservation signal 1167 including information on the transmission speed of the physical layer and the Wi-Fi frame length to all nodes within the coverage. Since the third terminal 1107 is located outside the coverage of the base station 1101, it does not receive a reservation signal from the base station 1101. However, the third terminal 1107 receives a signal from the first terminal 1103 . Terminal 3 1107 predicts the end time of the frame being transmitted based on the information included in the received preamble, and performs the L-SIG protection operation. Accordingly, the base station 1101 and the first terminal 1103 each transmit an independent reservation signal, thereby preventing channel occupation by a node located outside the coverage area. In addition, by suppressing signal transmission according to the L-SIG protection operation, transmission through a channel may also be additionally protected.

Examples of transmitting a reservation signal before and after LBT for channel occupation between downlink transmission and uplink transmission have been described through FIGS. 4 to 11 . In the above-described embodiments, it has been described that the transmission time of the reservation signal is derived from the time when the downlink transmission ends or the time when the LBT ends, but according to various embodiments, the terminal transmits data (eg, downlink transmission) ) is performed, it is possible to determine the transmission time of the reservation signal through separate signaling. The terminal receives prior information (eg, the position of the uplink subframe, the position of the downlink subframe after the maximum channel occupancy time, the end time of downlink transmission) according to various embodiments, or type information about the reservation signal to be used By receiving , information on whether the reservation signal is transmitted (embodiments of Figs. 7 to 9) and, if transmitted, information on the transmission time of the reservation signal (embodiments of Figs. 4 to 6 and Figs. 10 to 11) can be obtained have.

Hereinafter, a procedure for occupying a channel in transmission (eg, downlink transmission and downlink transmission) through FIGS. 12 to 15 is described.

Channel Occupation in Transmission

Referring to FIG. 12 , in step 1201, the base station identifies a channel occupancy period. According to the LTE-LAA standard, for fairness with other communication systems, a section in which a channel can be occupied is determined. For example, the maximum channel occupation period (COT) through the LBT may be 2ms, 3ms, 5ms, 8ms or 10ms. The base station may identify the channel occupation period of the downlink being transmitted.

In step 1203, the base station may determine whether downlink data transmission is completed within the channel occupation period. That is, the base station determines whether downlink data transmission is completed during the channel occupation period in order to determine whether it is necessary to transmit the reservation signal. When the downlink data transmission is completed within the channel occupancy period, the base station may end the procedure. On the other hand, when downlink data transmission is not completed within the channel occupation period, the base station needs to transmit a reservation signal in order to occupy the channel for the next downlink transmission. Accordingly, the base station can compare the channel occupation period and the downlink data transmission completion time.

In step 1205, the base station may transmit a reservation signal based on the determination. When the base station determines that downlink data transmission is not completed within the channel occupation period, the base station transmits a reservation signal in order to protect the channel occupation for the next downlink transmission. For example, the reservation signal may be a dummy signal. For another example, the reservation signal may be a Wi-Fi preamble. Hereinafter, the present disclosure will be described as an example of a dummy signal or a reservation signal, but is not limited thereto. That is, the reservation signal may include an arbitrary signal for the adjacent node to detect the channel occupancy by the base station through the channel sensing.

The base station occupies a channel through transmission of a reservation signal between transmissions, thereby reducing the probability of channel occupation by other adjacent nodes. The base station can maintain downlink transmission by preventing channel occupation by other neighboring nodes.

13A illustrates an example of a subframe for transmission of a reservation signal within transmission of a base station in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 13A , a base station 1301 may correspond to a base station 110 of FIG. 1 , and an adjacent terminal 1303 may correspond to a first terminal 120 , a second terminal 130 , or a third terminal 140 of FIG. 1 .

The time axis 1310 represents a flow of time when the base station 1301 performs signaling. A situation in which the base station 1301 transmits downlink data and a reservation signal through the time axis 1310 will be described.

Section 1330 shows the last subframe section included in the channel occupancy section. The base station 1301 requires an LBT execution time of 25 us to occupy a channel for downlink transmission. Accordingly, the base station 1301 may not transmit downlink data up to the subframe boundary of the period 1330. The length of the section 1331 in which the base station 1301 transmits downlink data and the section 1333 from the completion time of the downlink data to the subframe boundary may vary according to the type of the last subframe in the channel occupation section. For example, when the last subframe is the entire subframe, downlink data transmission may be terminated at a point in time earlier than the downlink subframe boundary by the length of one OFDM symbol. In this case, the period 1333 may have a time length of 71.3us corresponding to the length of one OFDM symbol.

During section 1335, the base station 1301 may transmit a dummy reservation signal 1339. Specifically, since the base station 1301 is the subject of downlink data transmission, the end time of the section 1331 can be accurately known, and accordingly, the base station 1301 can transmit the dummy reservation signal 1339 immediately after the downlink data transmission is completed. . The dummy reservation signal 1339 may be broadcast to a node within the coverage of the base station 1301 to inform that the current channel is not in an idle state.

During section 1337, the base station 1301 performs LBT. Since the base station 1301 did not transmit all of the downlink data before the end of the channel occupation period, it may perform LBT for downlink transmission after the release of the channel occupation. For example, the LBT performed by the base station 1301 is an LBT operation of category 2, and LBT may be performed for 25us.

The time axis 1320 shows the temporal flow of the neighboring terminal 1303. Specifically, a situation in which the adjacent terminal 1303 fails to occupy a channel for downlink transmission is described in the time axis 1320.

The adjacent terminal 1303 may perform LBT in order to transmit data. Neighboring terminal 1303, when performing LBT while downlink data is transmitted by the base station 1301, it can detect the energy above the threshold value. The adjacent terminal 1303 may determine channel occupation by another node (eg, the base station 1301 ) by detecting energy greater than or equal to the threshold value.

In addition, the adjacent terminal 1303 may perform LBT within the period 1333 corresponding to the subframe boundary time from the completion time of the downlink data transmission of the base station 1301. Here, section 1333 may include section 1335 and section 1337. When the adjacent terminal 1303 performs LBT in section 1335, the adjacent terminal 1303 receives the dummy reservation signal 1339 from the base station 1301, so it can determine that the current channel is not in an idle state. That is, the neighboring terminal 1303 may determine channel occupation by another node (eg, the base station 1301).

When the adjacent terminal 1303 performs LBT in section 1337, the adjacent terminal 1303 may perform LBT for at least the shortest time defined for LBT (eg, 25us). At this time, since the subject of the neighboring terminal 1303 is different from that of the base station 1301, it is not possible to know the exact transmission time, and due to a delay of a certain time due to the physical distance between the base station 1301 and the neighboring terminal 1303, the neighboring terminal 1303 is 25us Even if LBT is performed, energy above a threshold value can be detected. That is, the adjacent terminal 1303 cannot occupy a channel by a reservation signal transmitted by the base station 110 or downlink transmission (eg, transmission of a discovery reference signal (DRS)).

As described above, the probability that the neighboring terminal 1303 located in the vicinity of the base station 1301 will occupy the channel during downlink transmission of the base station 1301 may be reduced according to the transmission of the reservation signal of the base station 1301. Channel occupancy for downlink transmission of the base station 1301 may be guaranteed.

13B illustrates an example of a subframe for transmission of a reservation signal between transmissions of a terminal in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 13B , descriptions of the same section as the section shown in FIG. 13A and the same operation as the section shown in FIG. 13A will be omitted.

In section 1335, the base station 1301 transmits a Wi-Fi preamble reservation signal 1341. The adjacent terminal 1303 receives the Wi-Fi preamble reservation signal 1341 from the base station 1301 while performing LBT for downlink channel occupation, determines that the current channel is not in an idle state, and waits until the next LBT operation is performed. As described above, the Wi-Fi preamble transmitted as a reservation signal includes information on a transmission speed of a physical layer and a Wi-Fi frame length. Accordingly, the neighboring terminal 1303 predicts the end time of the currently transmitted Wi-Fi frame through information included in the received preamble and performs the L-SIG protection operation until the corresponding time point. That is, in order to protect the downlink transmission of the base station 1301, the adjacent terminal 1303 prevents interference by not transmitting a signal during the period 1343 until the calculated Wi-Fi frame end time. Accordingly, the base station 1301 can prevent channel occupation of the adjacent terminal and guarantee the channel occupation for downlink transmission by transmitting a reservation signal in transmission, and downlink transmission after channel occupation according to the L-SIG protection of the adjacent terminal 1303 can be protected up to

14A illustrates an example of a subframe for transmission of a reservation signal within transmission of a base station in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 14A , the base station 1401 may correspond to the base station 110 of FIG. 1 , and the adjacent terminal 1403 may include the first terminal 120 , the second terminal 130 , and the third terminal 140 of FIG. 1 . Hereinafter, in FIG. 14A , descriptions of the same section as the section shown in FIG. 13A and the same or similar operation as the section shown in FIG. 13A will be omitted.

The time axis 1410 represents a flow of time when the base station 1401 performs signaling. The time axis 1410 describes a situation in which the base station 1401 transmits downlink data and a reservation signal.

Section 1441 shows a section in which downlink data is transmitted in the last subframe of the channel occupancy section. The base station 1401 requires an LBT execution time of 25 us to occupy a channel for downlink transmission. Accordingly, the base station 1401 may not transmit downlink data up to the subframe boundary of the period 1440. That is, the subframe boundary and the completion time of downlink data transmission may not coincide. The length of the section 1441 in which the base station 1401 transmits downlink data and the section 1443 from the time when the downlink data transmission is completed to the subframe boundary may vary according to the type of the last subframe of the channel occupation section.

For example, when the last subframe is a partial end subframe, the transmission period of downlink data may be shorter than when the last subframe is an entire subframe. That is, in the section 1441, the section 1443 has a length of one OFDM symbol, that is, a time section greater than 71.3us. Accordingly, in order to occupy the channel for downlink transmission of the base station 1401, the length of the interval for transmitting the dummy reservation signal 1449 may be increased.

14B illustrates an example of a subframe for transmission of a reservation signal within transmission of a base station in a wireless communication system according to various embodiments of the present disclosure. Hereinafter, in FIG. 14B , descriptions of the same section as the section shown in FIG. 13B and the same or similar operation as the section shown in FIG. 13B will be omitted.

Referring to FIG. 14B , in section 1445, the base station 1401 transmits the Wi-Fi preamble reservation signal 1451. Specifically, the base station 1401 may broadcast the Wi-Fi preamble reservation signal 1451 to the neighboring terminal 1403 within the coverage area. Accordingly, the neighboring terminal 1403 receives the preamble and obtains information on the transmission rate of the physical layer and the length of the frame. Accordingly, the neighboring terminal 1403 may predict the end time of the currently transmitted Wi-Fi frame by performing a division operation on the Wi-Fi frame length by the transmission rate, and may perform the L-SIG protection operation until the predicted time. The L-SIG guard interval performed by the neighboring terminal 1403 is shown as an interval 1453. That is, in order to protect the downlink transmission of the base station 1401, the neighboring terminal 1403 prevents interference by not transmitting a signal during the period 1453 until the calculated Wi-Fi frame end time. Therefore, the base station 1401 can prevent channel occupation by neighboring nodes by transmitting a reservation signal in transmission including the Wi-Fi preamble and guarantee the occupation of the channel for downlink transmission, according to the L-SIG protection of the neighboring terminal 1403. Even downlink transmission after channel occupancy can be protected.

15 illustrates an example of a subframe for transmission of a reservation signal within transmission of a base station in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 15 , a base station 1501 may correspond to the base station 110 of FIG. 1 , and an adjacent terminal 1503 may include the first terminal 120 , the second terminal 130 , and the third terminal 140 of FIG. 1 .

The time axis 1510 represents a flow with respect to the time during which the base station 1501 performs signaling. The time axis 1510 describes a situation in which the base station 1501 transmits downlink data and a reservation signal. Specifically, when starting downlink transmission, the base station 1501 transmits the Wi-Fi preamble at the beginning of the frame in order to protect the channel occupancy from the Wi-Fi node. The preamble transmitted at the beginning of the frame includes information on the transmission rate of the physical layer and the length of the frame. Accordingly, the adjacent Wi-Fi node receives the preamble and obtains information on the transmission rate and the Wi-Fi frame length. Accordingly, the adjacent Wi-Fi node may predict the end time of frame transmission based on the acquired information. Specifically, the end time of frame transmission may be calculated by performing a division operation on the Wi-Fi frame length by the transmission rate. According to the Wi-Fi communication system, the transmission time that can be protected by transmitting the Wi-Fi preamble before the Wi-Fi frame is up to 5.484 ms. A period 1535 shows an L-SIG guard period protected by a preamble transmitted at the beginning of a frame.

According to the LTE-LAA standard, when a channel is occupied by performing LBT, the maximum channel occupancy period is 2ms, 3ms, 5ms, 8ms, or 10ms. Therefore, when the maximum channel occupancy period is 8 ms or 10 ms, downlink transmission after the L-SIG guard period cannot be protected. Accordingly, the base station 1501 transmits the Wi-Fi preamble reservation signal 1539 during the period 1533. Specifically, the base station 1501 may broadcast the Wi-Fi preamble reservation signal 1539 to all nodes within coverage. The base station 1501 performs an LBT operation to occupy a continuous downlink channel. Therefore, in order to secure the LBT execution time of 25us, the base station 1501 transmits downlink data except for the last OFDM symbol in the subframe at which the guard period ends. Downlink data transmission except for the last OFDM symbol is shown in section 1530. The base station 1501 may transmit the Wi-Fi preamble reservation signal 1539 during an interval 1533 corresponding to one OFDM symbol length. Since the length of one OFDM symbol is 71.3us, in order to prevent occupation of a continuous downlink channel by other nodes, the base station 1501 may continuously transmit a reservation signal during section 1533.

A Wi-Fi node among a plurality of neighboring nodes can protect continuous downlink transmission by predicting an end time of a transmission frame through a preamble included in a reservation signal and performing an L-SIG protection operation. Interval 1537 shows an L-SIG guard interval through a preamble included in a reservation signal in transmission. In addition, nodes other than the Wi-Fi node among a plurality of neighboring nodes may determine that the current channel is not idle by the reservation signal transmitted in section 1533, and wait until the next LBT operation time. That is, the base station 1501 can guarantee continuous downlink occupation by transmitting a reservation signal during one period of an OFDM symbol during downlink transmission. In addition, the base station 1501 can additionally protect the transmission period after the occupation of the continuous downlink through L-SIG protection by transmitting a reservation signal including the Wi-Fi preamble.

Examples of performing channel occupation through an intra-transmission reservation signal have been described with reference to FIGS. 12 to 15 . 12 to 15 illustrate that a reservation signal is transmitted in downlink transmission, but is not limited thereto. That is, it goes without saying that channel occupation in uplink transmission may be performed by the terminal by transmitting a reservation signal in uplink transmission.

Methods according to the embodiments described in the claims or specifications of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured to be executable by one or more processors in an electronic device (device). One or more programs include instructions for causing an electronic device to execute methods according to embodiments described in a claim or specification of the present disclosure.

Such programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable ROM (electrically erasable programmable read only memory, EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other It may be stored in an optical storage device or a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of some or all thereof. In addition, each configuration memory may be included in plurality.

In addition, the program is transmitted through a communication network consisting of a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. It may be stored on an attachable storage device that can be accessed. Such a storage device may be connected to a device implementing an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may be connected to the device implementing the embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed in the singular or plural according to the specific embodiments presented. However, the singular or plural expression is appropriately selected for the situation presented for convenience of description, and the present disclosure is not limited to the singular or plural component, and even if the component is expressed in plural, it is composed of the singular or singular. Even an expressed component may be composed of a plurality of components.

Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments and should be defined by the claims described below as well as the claims and equivalents.

Claims (31)

A method of operating a terminal for uplink transmission in an unlicensed band of a wireless communication system, the method comprising:
A process of receiving downlink data from a base station;
In a subframe, the process of receiving a first reservation signal from the base station;
After detecting the first reservation signal, the process of performing a listen before talk (LBT) in the subframe;
Based on the end time of the LBT and the subframe boundary of the next subframe, the process of transmitting a second reservation signal in the subframe;
Based on the subframe boundary, comprising the step of transmitting uplink data to the base station,
The reception of the first reservation signal, the performance of the LBT and the transmission of the second reservation signal will be performed within one symbol interval.
The method according to claim 1, wherein the subframe is a full subframe or an ending partial subframe.
The method according to claim 1, wherein the second reservation signal comprises a dummy signal or a Wi-Fi preamble,
The Wi-Fi preamble includes information on a transmission rate of a physical layer and a length of a frame.
The method according to claim 1, wherein the second reservation signal is transmitted within the interval from the end time of the LBT to the subframe boundary.
The method according to claim 1,
The first reservation signal includes a dummy signal or a Wi-Fi preamble.
The method according to claim 1, wherein the first reservation signal is transmitted from the base station immediately after the transmission of the downlink data is completed,
The LBT method is performed after receiving the first reservation signal.
delete In a terminal for uplink transmission in an unlicensed band of a wireless communication system,
transceiver;
a processor coupled to the transceiver, the processor comprising:
Receive downlink data from the base station,
In the subframe, receiving a first reservation signal from the base station,
After detecting the first reservation signal, LBT (listen before talk) is performed in the subframe,
Based on the end time of the LBT and the subframe boundary of the next subframe, transmit a second reservation signal in the subframe,
Transmitting uplink data to the base station based on the subframe boundary,
The reception of the first reservation signal, the performance of the LBT and the transmission of the second reservation signal will be performed within one symbol interval, the terminal.
The terminal of claim 8, wherein the subframe is a full subframe or an ending partial subframe.
The method according to claim 8, wherein the second reservation signal comprises a dummy signal or a Wi-Fi preamble,
The Wi-Fi preamble includes information on a transmission rate of a physical layer and a length of a frame.
The terminal of claim 8, wherein the first reservation signal is transmitted within a period from the end time of the LBT to the subframe boundary.
9. The method of claim 8,
The first reservation signal is a terminal including a dummy signal or a Wi-Fi preamble.
The method according to claim 8, wherein the first reservation signal is transmitted from the base station immediately after the transmission of the downlink data is completed,
The LBT terminal is performed after receiving the first reservation signal.
delete In the operating method of a base station for downlink transmission in an unlicensed band of a wireless communication system,
The process of transmitting downlink data to the terminal;
Transmitting a first reservation signal in a subframe based on the completion time of the transmission, a predetermined time, and a subframe boundary;
After the end of the LBT (listen before talk) of the terminal, the process of receiving a second reservation signal in the subframe and the process of receiving uplink data from the terminal based on the subframe boundary of the next subframe, ,
The predetermined time is the LBT execution time of the terminal for transmitting the uplink data,
The reception of the first reservation signal, the performance of the LBT and the transmission of the second reservation signal are performed within one symbol interval.
The method of claim 15 , wherein the subframe is a full subframe or an ending partial subframe.
The method according to claim 15, wherein the second reservation signal comprises a dummy signal or a Wi-Fi preamble,
The Wi-Fi preamble includes information on a transmission rate of a physical layer and a length of a frame.
The method according to claim 15, wherein the second reservation signal is transmitted within a period from the end time of the transmission of the downlink data to the start time of the predetermined time,
The end point of the predetermined time coincides with the subframe boundary.
16. The method of claim 15,
The second reservation signal includes a dummy signal or a Wi-Fi preamble.
The method of claim 15 , wherein the first reservation signal is received within a period from the end of the predetermined time to the subframe boundary.
delete delete In a base station for downlink transmission in an unlicensed band of a wireless communication system,
transceiver;
a processor coupled to the transceiver, the processor comprising:
transmit downlink data to the terminal;
Transmitting a first reservation signal in a subframe based on the completion time of the transmission, a predetermined time and a subframe boundary,
After the end of the LBT (listen before talk) of the terminal, receiving a second reservation signal in the subframe,
Receive uplink data from the terminal based on the subframe boundary of the next subframe,
The predetermined time is the LBT execution time of the terminal for transmitting the uplink data,
The base station that the reception of the first reservation signal, the performance of the LBT and the transmission of the second reservation signal is performed within one symbol interval. delete delete delete delete delete delete delete delete

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